# 7+ C# Prime Number Checker Program Examples

This post contains a total of 7+ Hand-Picked C Sharp Prime number checker Program Examples with Source Code. All these prime number checker programs are made using C Sharp Programming Language.

You can use the source code of these examples with credits to the original owner.

## C Sharp Prime Number Checker Programs

### 1. By Zarthah

Made by Zarthah. C# Program to Check if numbers in a given range are prime or not, the program by default checks the numbers in range 10 – 100. Source

```If its 'true' it means its a prime number
-10 = False
-9 = False
-8 = False
-7 = False
-6 = False
-5 = False
-4 = False
-3 = False
-2 = False
-1 = False
0 = False
1 = False
2 = True
3 = True
4 = False
5 = True```
``````using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;

namespace SoloLearn
{
class Program
{
static bool prime(int num)
{
if(num > 1)
{
if(num == 2)
return true;

for(int i = 2; i <= num/2; i++)
{
if(num % i == 0)
return false;
}
return true;
}
return false;
}
static void Main(string[] args)
{
Console.WriteLine("If its 'true' it means its a prime number");

// For example, we will check from -10 to 100, which those numbers are the prime number.
for(int i = -10; i <= 100; i++)
{
Console.Write(Convert.ToString(i));
Console.Write(" = ");
Console.WriteLine(prime(i));
}
}
}
}
``````

### 2. By Canny

Made by Canny. A simple program to check if a Number is PRIME or NOT A PRIME NUMBER. Source

```10
10 is NOT A PRIME NUMBER```
``````using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
namespace SoloLearn
{
class Program
{
static void Main(string[] args)
{
double num, divisor = 1, counter=0;

do
{
if(num % divisor == 0)
{

counter++; //counts the factors
divisor++;
}
else
divisor++;
}

while(divisor<=num);

if(counter==2) //TRUE if the number has two factors
Console.Write(\$"{num} is a PRIME NUMBER");
else
Console.Write(\$"{num} is NOT A PRIME NUMBER");
}
}
}
``````

### 3. By Samuel Kurnas

```7
7 is prime number```
``````using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;

namespace SoloLearn
{
class Program
{
static void Main(string[] args)
{
//insert some number

Console.WriteLine(number + " is prime number");
else
Console.WriteLine(number + " is not prime number");
}

{
if (number == 1)
return false;

if (number == 2)
return true;

int loops = Convert.ToInt32(Math.Floor(Math.Sqrt(number)));

for (int i = 2;i<=loops;i++)
{
//modulo
if (number%i == 0)
return false;
}

return true;
}
}
}
``````

### 4. By ermain F

Made by ermain F. Prime number checker program that takes an arbitrary integer and determines whether it is prime. Source

```The number you entered is 12
12 is not a prime number```
``````using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;

namespace Integers
{
{

static bool isAPrime( int numba)
{
int factor =0;
for (int loop=1; loop<=numba; loop++){
if ( numba % loop == 0)
factor++;
}

if (factor == 2)
return true;

return false;
}

static void Main(string[] args)
{
Console.WriteLine("Prime Number Checker version 1.0.0\nCode By Germain.F..................\n\n");
Console.WriteLine ("The number you entered is {0}", number);

if ( isAPrime(number) )
Console.WriteLine ("{0} is a prime number", number);
else
Console.WriteLine ("{0} is not a prime number", number);

Console.WriteLine("\n.......................Please don't forget to leave a like or a comment.\nThanks for testing!");

}
}
}
``````

### 5. By Mikeul

```9
9 is not a prime number```
``````using System;
namespace Prime
{
class Program
{
static void Main(string[] args)
{
if(input.IsPrime())
Console.WriteLine(\$"{input} is a prime number");
else
Console.WriteLine(\$"{input} is not a prime number");
}
}
public static class Count
{
public static bool IsPrime(this int n)
{
if(n < 2)
return false;
for(int i = 2; i <= n/2; i++)
if(n % i == 0)
return false;
return true;
}
}
}
``````

## 6. By Domagoj Puljiฤ

```3
Number is prime.```
``````using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;

namespace SoloLearn
{
class Program
{
static void Main(string[] args)
{
if(isPrime(n)){
Console.WriteLine("Number is prime.");
}
else {
Console.WriteLine("Number is not prime.");
}
}
static bool isPrime(int number)
{
if(number==1 || number==0){
return false;
}
for(int i=2;i<=Math.Sqrt(number);i++){
if(number%i==0){
return false;
}
}
return true;
}
}
}
``````

### 7. By Damon Keane

Made by Damon Keane. A simple C Sharp program to see if the input number is prime or not. Source

```15
Not Prime```
``````using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;

namespace SoloLearn
{
class Program
{
public static void Prime(int n) {
bool prime = true;

int x = Convert.ToInt32(Math.Sqrt(n));
if(n == 1)
{
prime = false;
}
for(int i = 2; i <= x; i++)
{
if(n%i == 0)
{
prime = false;
}
}
if(prime)
{
Console.WriteLine("Is Prime");
}
else {
Console.WriteLine("Not Prime");
}
}
static void Main(string[] args)
{
Prime(num);
}
}
}
``````

### 8. By Divi

Made by Divi. Enter any integer ( not more than 32bit) and the program will tell if the number is prime or not. Source

```19
19 is a prime number.```
``````using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;

namespace SoloLearn
{
class Program
{
static void Main()
{
int x;